The art of marsh-thinking as ecological care

Organic compounds can constitute roughly half of the sub-micron aerosol mass in the troposphere, necessitating an accurate representation of organic aerosol (OA) in Earth system models (ESMs) to better capture aerosol-climate feedbacks. The secondary fraction of OA (SOA), however, formed through the oxidation of various volatile organic compounds (VOCs) from both natural and anthropogenic sources, complicates the description of OA in ESMs. Most ESMs either assume a non-volatile SOA produced with a constant yield from known precursors or provide a simplistic depiction of its volatility derived from biogenic VOCs, treating the primary fraction of OA (POA) as non-reactive and non-volatile. This approach often fails to accurately reproduce observed OA atmospheric measurement. On the other hand, biological materials such as bacteria, fungal spores, and various fragments released by living organisms into the atmosphere have been widely identified as part of the super-micron OA mass, which most ESMs also inadequately represent.In the context of the H.F.R.I. project REINFORCE, we focus on improving the representation of atmospheric composition in Earth System Models (ESMs). We present simulations using the volatility basis set (VBS) approach to represent SOA formation, along with incorporating the organic fraction of bioaerosols. These developments are implemented in the state-of-the-art ESM, EC-Earth version 3, which includes interactive aerosols and atmospheric chemistry (EC-Earth3-AerChem). A lite version of the well-documented aerosol module ORACLE, which allows for relatively limited computing resource consumption, has been coupled to the CTM component of EC-Earth3-AerChem to calculate the partitioning and chemical evolution of POA vapors and their changes in volatility. The formation of SOA from semivolatile organic compounds (SVOCs) and intermediate-volatility organic compounds (IVOCs) has been added to the existing SOA formation scheme from biogenic VOCs in the model. Moreover, the three main types of bioaerosols—bacteria, fungal spores, and pollen grains—have been implemented into the model based on interactive bioaerosol schemes that depend on ecosystem types, the leaf area index (LAI), and various meteorological parameters. Bioaerosols in EC-Earth3-AerChem can also be transferred to the soluble aerosol coarse mode due to atmospheric aging processes. Overall, our efforts aim to bridge the gap between model simulations and observations, thereby enhancing our understanding of OA climate impacts.

<p>The climate on Earth arises from multiple interactions between the different spheres, including the biosphere. Within the biosphere, the organisms composing the various types of ecosystem are characterized by a set of traits involved in biological processes that can influence the climate system. Identifying and integrating these traits into models such as earth system models (ESM) is thus crucial to predict the future of earth climate. While an important number of biological processes are similar, the amount and the type of traits considered to represent these processes can vary considerably among ecosystem types in current ESMs. Such inconsistencies could bias our perception of the global influence of biosphere on climate dynamics. Here we first list the biological traits that have been included in the terrestrial and oceanic modules of the CMIP5 Earth system models. By comparing the traits and associated processes, we reveal consistencies and inconsistencies in trait representation among both ecosystem types. Based on a critical evaluation we propose a new conceptual framework that allows to describe the climate relevant traits in a consistent way in terrestrial and oceanic modules of ESMs. This framework can also be used to identify new traits characterizing terrestrial and/or marine ecosystems, and to integrate them in ESMs.</p>

Soil properties rather than climate and ecosystem type control the vertical variations of soil organic carbon, microbial carbon, and microbial quotient

  With climate warming, atmospheric vapor pressure deficit (VPD) shows an increasing trend, which may restrict plant growth. However, there is still uncertainty regarding the response mechanisms of plant transpiration and photosynthesis to VPD, soil moisture, and their interactions. This uncertainty leads to significant discrepancies among different Earth system models when simulating the impact of atmospheric drought on terrestrial ecosystem productivity, and it constitutes a crucial source of uncertainty in predicting the global carbon balance of land ecosystems in the future. In this study, through analyzing field measurements, satellite-derived data, and Earth system model (ESM) simulations, we reveal a similar threshold response pattern of GPP to VPD for most ecosystem types, where GPP initially increases and then decreases with increasing VPD. When VPD exceeds these thresholds, increased soil moisture loss and atmospheric drought stress lead to reduced stomatal conductance and lowered light saturation point in plant leaves, decreasing terrestrial ecosystems' productivity. Existing Earth system models emphasize the influence of CO2 fertilization on land ecosystem productivity and predict a continuous increase in global terrestrial GPP throughout the 21st century. However, these models also indicate a significant reduction in GPP of low-latitude land ecosystems when VPD exceeds the threshold. This finding highlights the impact of climate warming on VPD and implies potential limitations on future land ecosystem productivity due to increased atmospheric water demand. This study suggests incorporating the interactions among VPD, soil moisture, and canopy conductance into Earth system models to enhance the predictive capacity for the response of land ecosystems to climate change.

Vasopressin and oxytocin as neurohormonal mediators of MDMA (ecstasy) sociosexual behavioural effects

Root effects on the temperature sensitivity of soil respiration depend on climatic condition and ecosystem type

<p>Tropical forests play a key role in the flux of terrestrial carbon (C). However, recent studies show tropical forest are losing over the years the ability to sink C from the atmosphere, one of the best explanations for that is the climate change caused by humanity in the last centuries and accelerating slightly every year. One of the ways to understand the changes in C fluxes in forest ecosystems in the short, medium, and long term are the Earth system models (ESMs). Nevertheless, simulations demonstrate that ESMs are not able to represent the decline in C sink by tropical forests in recent decades. Experiments that fertilize the atmosphere with carbon dioxide (eCO<sub>2</sub>) are essential to reduce uncertainties in future ESM projections about the possible effects of eCO<sub>2</sub> on the carbon cycle. Open top chamber (OTC) allow the exposure of understory vegetation to eCO<sub>2</sub> allowing the control and monitoring of the microenvironment in which they are inserted. Here, we describe the OTC system currently operating in the Amazon Free-Air CO<sub>2</sub> Enrichment research program (AmazonFACE) in a mature forest in Central Amazonia, the analysis period is from 01/01/2020 to 12/31/2020. Each OTC is 2.40 m in diameter by 3.00 m in height, in which the concentration of CO<sub>2</sub> ([CO<sub>2</sub>]) is monitored minute-by-minute using infrared gas analyzers, allowing the spatial and temporal control of [CO<sub>2</sub>]. The operation consists of keeping the [CO<sub>2</sub>] in the treatment OTCs (<em>i.e</em>., with eCO<sub>2</sub>) ≈ 200 µmol. mol<sup>–</sup><sup>1</sup> above the [CO<sub>2</sub>] of the control OTCs (<em>i.e.,</em> without eCO<sub>2</sub>) in the daytime (between 6:00 am - 6:00 pm). The [CO<sub>2</sub>] measurements on the treatment and control OTCs show that the desired concentration was successfully delivered, +262.4 ± 25.5 µmol / mol (mean ± SD) of the desired setpoint, <em>i.e.</em>, 31 % above setpoint target. The eCO<sub>2</sub> in the treatment OTCs worked 91% of the analyzed operational time, the remaining time was wasted with engineering failures (3%) and problems with the supply of CO<sub>2</sub> (6%). The system was able to maintain the [CO<sub>2</sub>] above the setpoint, showing that the system configuration is capable of exposing understory vegetation even in a highly complex environment. The results demonstrate that the <em>in-situ </em>OTC system presented can be reproduced in different types of ecosystems, allowing better knowledge about metabolic processes that occur between atmosphere-plant-soil.</p>

Modeling carbon burial along the land to ocean aquatic continuum: Current status, challenges and perspectives

Symbiotic nitrogen (N) fixation (SNF), replenishing bioavailable N for terrestrial ecosystems, exerts decisive roles in N cycling and gross primary production. Nevertheless, it remains unclear what determines the variability of SNF rate, which retards the accurate prediction for global N fixation in earth system models. This study synthesized 1230 isotopic observations to elucidate the governing factors underlying the variability of SNF rate. The SNF rates varied significantly from 3.69 to 12.54 g N m-2 year-1 across host plant taxa. The traits of host plant (e.g. biomass characteristics and taxa) far outweighed soil properties and climatic factors in explaining the variations of SNF rate, accounting for 79.0% of total relative importance. Furthermore, annual SNF yield contributed to more than half of N uptake for host plants, which was consistent across different ecosystem types. This study highlights that the biotic factors, especially host plant traits (e.g. biomass characteristics and taxa), play overriding roles in determining SNF rate compared with soil properties. The suite of parameters for SNF lends support to improve N fixation module in earth system models that can provide more confidence in predicting bioavailable N changes in terrestrial ecosystems.

Chapter 2 - Links between attachment and social information processing: examination of intergenerational processes

Land use change is one of the most direct and significant impacts of human activities on the Earth system. It not only changes the physical characteristics of the land surface, but also affects the energy, water, and material cycles of the Earth, and thus affects the global and regional climate change and ecosystem services. Among them, the impact of land use change on the carbon cycle is particularly important, because the carbon cycle is one of the most basic and critical cycles in the Earth system. It determines the greenhouse effect and climate sensitivity of the Earth, and also affects the biodiversity and productivity. This paper systematically analyzes the impact and mechanism of the carbon effects of land use change on different ecosystem types, different geographic regions, different climate conditions, different land use modes and management measures from different angles and levels, using various methods and models, evaluates the factors such as the size, direction, persistence, and sustainability of the carbon effects of land use change, proposes some evaluation and promotion of management techniques and measures, as well as policy suggestions and institutional designs for the carbon effects, and provides scientific basis and reference suggestions for the optimization and control of the carbon effects of land use change.

Meta-analysis shows non-uniform responses of above- and belowground productivity to drought

Soil anammox is an environmentally-friendly way to eliminate reactive nitrogen (N) without generating nitrous oxide. Nevertheless, the current earth system models have not incorporated the anammox due to the lack of parameters in anammox rates on a global scale, limiting the accurate projection for N cycling. A global synthesis with 1212 observations from 89 peer-reviewed papers showed that the average anammox rate was 1.60 ± 0.17 nmol N g-1 h-1 in terrestrial ecosystems, with significant variations across different ecosystems. Wetlands exhibited the highest rate (2.17 ± 0.31 nmol N g-1 h-1 ), followed by croplands at 1.02 ± 0.09 nmol N g-1 h-1 . The lowest anammox rates were observed in forests and grasslands. The anammox rates were positively correlated with the mean annual temperature, mean annual precipitation, soil moisture, organic carbon (C), total N, as well as nitrite and ammonium concentrations, but negatively with the soil C:N ratio. Structural equation models revealed that the geographical variations in anammox rates were primarily influenced by the N contents (such as nitrite and ammonium) and abundance of anammox bacteria, which collectively accounted for 42% of the observed variance. Furthermore, the abundance of anammox bacteria was well simulated by the mean annual precipitation, soil moisture, and ammonium concentrations, and 51% variance of the anammox bacteria was accounted for. The key controlling factors for soil anammox rates differed from ecosystem type, e.g., organic C, total N, and ammonium contents in croplands, versus soil C:N ratio and nitrite concentrations in wetlands. The controlling factors in soil anammox rate identified by this study are useful to construct an accurate anammox module for N cycling in earth system models.

Abstract. Carbon (C) and nitrogen (N) cycles are coupled in terrestrial ecosystems through multiple processes including photosynthesis, tissue allocation, respiration, N fixation, N uptake, and decomposition of litter and soil organic matter. Capturing the constraint of N on terrestrial C uptake and storage has been a focus of the Earth System Modeling community. However, there is little understanding of the trade-offs and sensitivities of allocating C and N to different tissues in order to optimize the productivity of plants. Here we describe a new, simple model of ecosystem C–N cycling and interactions (ACONITE), that builds on theory related to plant economics in order to predict key ecosystem properties (leaf area index, leaf C : N, N fixation, and plant C use efficiency) based on the outcome of assessments of the marginal change in net C or N uptake associated with a change in allocation of C or N to plant tissues. We simulated and evaluated steady-state ecosystem stocks and fluxes in three different forest ecosystems types (tropical evergreen, temperate deciduous, and temperate evergreen). Leaf C : N differed among the three ecosystem types (temperate deciduous < tropical evergreen < temperature evergreen), a result that compared well to observations from a global database describing plant traits. Gross primary productivity (GPP) and net primary productivity (NPP) estimates compared well to observed fluxes at the simulation sites. Simulated N fixation at steady-state, calculated based on relative demand for N and the marginal return on C investment to acquire N, was an order of magnitude higher in the tropical forest than in the temperate forest, consistent with observations. A sensitivity analysis revealed that parameterization of the relationship between leaf N and leaf respiration had the largest influence on leaf area index and leaf C : N. A parameter governing how photosynthesis scales with day length had the largest influence on total vegetation C, GPP, and NPP. Multiple parameters associated with photosynthesis, respiration, and N uptake influenced the rate of N fixation. Overall, our ability to constrain leaf area index and allow spatially and temporally variable leaf C : N can help address challenges simulating these properties in ecosystem and Earth System models. Furthermore, the simple approach with emergent properties based on coupled C–N dynamics has potential for use in research that uses data-assimilation methods to integrate data on both the C and N cycles to improve C flux forecasts.

Fire is a crucial process of the Earth's system and contributes to large emissions of carbon and nitrogen (N), including ammonia (NH 3 ) and nitrogen oxides (NO x ). Q. Chen et al. (2025, https://doi.org/10.1029/2024GL112396 ) reveals that extreme boreal fires emit unexpectedly high levels of NH 3 , comparable to large agricultural sources. The partitioning between NH 3 and NO x fire emissions varies across different ecosystem types, leading to divergent impacts on the N cycle. New advancements in Earth System Models and more specifically, a better representation of the N cycle would offer a powerful framework for enhancing our understanding of fire reactive nitrogen (N r ) emissions' impacts on atmospheric chemistry, ecosystems, and the global nitrogen cycle.